Recently, we use Kubernetes for our project. Yesterday, a problem haunted me severely: even I have pushed the docker image to the GCR (Goolge Container Registry), the pod in Kubernetes will still use the stale image.
I tried many ways to solve the problem: removing the image in GCR, removing the image in local laptop, rebuild the image again and again. And finally I have found the reason and also realised that I am still a stupid starter on Kubernetes.
The reason for pod to use stale docker image is: the Kubernetes will (and should, I think) cache the docker images it used before for speed. Hence if you want it to re-pull image forcedly. You should use configuration item imagePullPlicy(ref), like:

    - name: uses-private-image
      imagePullPolicy: Always  

Fortunately I can debug my docker image correctly now…